The Greater Dublin Water Supply Strategic Study

 The rapid growth in population and commercial and industrial development over the past few years has placed major strains on our water supply. The Greater Dublin Water Supply Strategic Study, commissioned by the Department of the Environment back in 1996 sets out an investment programme up to 2016. 

The Dublin Region Water Supply is sourced from the four following water treatment plants, Roundwood, Ballyboden, Leixlip and Ballymore Eustace.  The study outlined the need to both increase water production and conserve the existing supplies to meet the ever-increasing demand.  Dublin City Council Engineering Department has initiated schemes to continue and improve the provision of a clean and reliable water supply. Some of the needs are listed below.  

• Increase Water Production at Ballymore Eustace
• Reduce Water Leakage in the Greater Dublin Region
• Rehabilitate or Replace existing Watermains
• Identify new water sources
• Improvement works to existing Storage Reservoirs

Ballymore Eustace

Expansion of BME Water Treatment Plant output by 26% from 250Mld to 318Mld. Construction of new filters, sedimentation tanks, reservoir, administration and laboratory facilities. Scheme is currently at construction.

Dublin Region Storage Study

A Strategic Study has been completed to determine the projected water demands for the Greater Dublin Area up to the Year 2031 and to identify future drinking water storage requirements for the Region. Schemes are listed in Water Services Investment Programme (WSIP) 2010 – 2012.

Stillorgan Reservoirs ByPass Pipeline

A Scheme has been constructed to create a bypass pipeline around Stillorgan Storage Reservoirs - thus improving security of supply to consumers by enabling, if/when required, delivery of drinking water from the Water Treatment Works, directly into the distribution watermains.

 Saggart Chlorination

The current method of disinfection of the water supply at Saggart is Chlorination. This is achieved by injecting chlorine gas into the water supply network via conventional chlorine gas cylinders. Whilst this facility has performed satisfactorily it was installed initially as a temporary pilot facility and it is now proposed to upgrade the plant by installing a more modern and safer facility. The OSEC system utilises hypochlorite liquid solution for disinfection thus removing the necessity for the usage of chlorine gas cylinders.
Scheme is completed and commissioning works are to be completed during summer 2010.

 Vartry Covered Reservoir

The Greater Dublin Water Supply Strategic Development Plan” noted that open storage of treated water was undesirable, and recommended that an alternative to open storage be implemented.

The new covered reservoir works consist of the following:

• The construction of a Reinforced Concrete Covered Service Reservoir with a total capacity of 13,000 cubic metres. The construction of two Reinforced Concrete Slow Sand Filters Beds. To ensure that the existing daily supply output from the Water Treatment Plant is not impaired during construction, the contract requires that that the above works are constructed in a particular sequence.
• Construction is completed.

Ballyboden Covered Reservoir

The 1996 General des Eaux / M.C.O’Sullivan “Greater Dublin Water Supply Strategic Development Plan” noted that open storage of treated water was undesirable, and recommended that an alternative to open storage be implemented.

 To comply with the above recommendation it is now proposed to construct a New Covered Reservoir of 40 million litres capacity and a Contact Tank of 5 million litres capacity at Ballyboden. A new Pumping Station for the pumped supply to Woodtown Reservoir is also included in the contract.

Bohernabreena Spillways

The spillways upgrading is been undertaken to bring the spillways up to modern safety standards. Construction is completed.

The scheme consists of the following: 

• The phased demolition of the existing stilling basins, weirs and spillways at the Upper and Lower Reservoirs and their replacement with enlarged and deeper reinforced concrete structures.  The upper spillway to include two new guidewalls. Ancillary works include pipelaying, road widening, culverting of streams, removal and reinstatement of mature trees and wavewall improvements.

Vartry Tunnel Rehabilitation and Upgrading

This tunnel is a critical artery for the supply of water to the Dublin/Wicklow area. Its daily flow of 80 million litres represents some 25% of the total of Dublin City Council Supply to the Greater Dublin Area. This tunnel was constructed in the 1860’s some 133 years ago, so it is appropriate that the question of its reliability be examined at this time. Failure of the tunnel would lead to the loss of water supply to vast areas of South Dublin/ North Wicklow, much of which cannot be serviced, even on a temporary basis, by any alternative Dublin supply source. The schemes is listed in WSIP 2010-2012 to advance subject to funding and staff resources.